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5d48545e PBG |
1 | /* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c. |
2 | Original copyright notice follows: | |
3 | ||
4 | Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc. | |
5 | This file is part of the GNU C Library. | |
6 | ||
7 | The GNU C Library is free software; you can redistribute it and/or | |
8 | modify it under the terms of the GNU Lesser General Public | |
9 | License as published by the Free Software Foundation; either | |
10 | version 2.1 of the License, or (at your option) any later version. | |
11 | ||
12 | The GNU C Library is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public | |
18 | License along with the GNU C Library; if not, write to the Free | |
19 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
20 | 02111-1307 USA. */ | |
21 | #include <unistd.h> | |
22 | ||
23 | #include <stdbool.h> | |
24 | #include <stdlib.h> | |
25 | #include <string.h> | |
26 | #include <errno.h> | |
27 | #include <limits.h> | |
28 | ||
29 | #ifndef TEST | |
37185b33 | 30 | #include <um_malloc.h> |
5d48545e PBG |
31 | #else |
32 | #include <stdio.h> | |
33 | #define um_kmalloc malloc | |
34 | #endif | |
37185b33 | 35 | #include <os.h> |
5d48545e PBG |
36 | |
37 | /* Execute FILE, searching in the `PATH' environment variable if it contains | |
38 | no slashes, with arguments ARGV and environment from `environ'. */ | |
39 | int execvp_noalloc(char *buf, const char *file, char *const argv[]) | |
40 | { | |
41 | if (*file == '\0') { | |
42 | return -ENOENT; | |
43 | } | |
44 | ||
45 | if (strchr (file, '/') != NULL) { | |
46 | /* Don't search when it contains a slash. */ | |
47 | execv(file, argv); | |
48 | } else { | |
49 | int got_eacces; | |
50 | size_t len, pathlen; | |
51 | char *name, *p; | |
52 | char *path = getenv("PATH"); | |
53 | if (path == NULL) | |
54 | path = ":/bin:/usr/bin"; | |
55 | ||
56 | len = strlen(file) + 1; | |
57 | pathlen = strlen(path); | |
58 | /* Copy the file name at the top. */ | |
59 | name = memcpy(buf + pathlen + 1, file, len); | |
60 | /* And add the slash. */ | |
61 | *--name = '/'; | |
62 | ||
63 | got_eacces = 0; | |
64 | p = path; | |
65 | do { | |
66 | char *startp; | |
67 | ||
68 | path = p; | |
69 | //Let's avoid this GNU extension. | |
70 | //p = strchrnul (path, ':'); | |
71 | p = strchr(path, ':'); | |
72 | if (!p) | |
73 | p = strchr(path, '\0'); | |
74 | ||
75 | if (p == path) | |
76 | /* Two adjacent colons, or a colon at the beginning or the end | |
77 | of `PATH' means to search the current directory. */ | |
78 | startp = name + 1; | |
79 | else | |
80 | startp = memcpy(name - (p - path), path, p - path); | |
81 | ||
82 | /* Try to execute this name. If it works, execv will not return. */ | |
83 | execv(startp, argv); | |
84 | ||
85 | /* | |
86 | if (errno == ENOEXEC) { | |
87 | } | |
88 | */ | |
89 | ||
90 | switch (errno) { | |
91 | case EACCES: | |
92 | /* Record the we got a `Permission denied' error. If we end | |
93 | up finding no executable we can use, we want to diagnose | |
94 | that we did find one but were denied access. */ | |
95 | got_eacces = 1; | |
96 | case ENOENT: | |
97 | case ESTALE: | |
98 | case ENOTDIR: | |
99 | /* Those errors indicate the file is missing or not executable | |
100 | by us, in which case we want to just try the next path | |
101 | directory. */ | |
102 | case ENODEV: | |
103 | case ETIMEDOUT: | |
104 | /* Some strange filesystems like AFS return even | |
105 | stranger error numbers. They cannot reasonably mean | |
106 | anything else so ignore those, too. */ | |
107 | case ENOEXEC: | |
108 | /* We won't go searching for the shell | |
109 | * if it is not executable - the Linux | |
110 | * kernel already handles this enough, | |
111 | * for us. */ | |
112 | break; | |
113 | ||
114 | default: | |
115 | /* Some other error means we found an executable file, but | |
116 | something went wrong executing it; return the error to our | |
117 | caller. */ | |
118 | return -errno; | |
119 | } | |
120 | } while (*p++ != '\0'); | |
121 | ||
122 | /* We tried every element and none of them worked. */ | |
123 | if (got_eacces) | |
124 | /* At least one failure was due to permissions, so report that | |
125 | error. */ | |
126 | return -EACCES; | |
127 | } | |
128 | ||
129 | /* Return the error from the last attempt (probably ENOENT). */ | |
130 | return -errno; | |
131 | } | |
132 | #ifdef TEST | |
133 | int main(int argc, char**argv) | |
134 | { | |
135 | char buf[PATH_MAX]; | |
136 | int ret; | |
137 | argc--; | |
138 | if (!argc) { | |
139 | fprintf(stderr, "Not enough arguments\n"); | |
140 | return 1; | |
141 | } | |
142 | argv++; | |
143 | if (ret = execvp_noalloc(buf, argv[0], argv)) { | |
144 | errno = -ret; | |
145 | perror("execvp_noalloc"); | |
146 | } | |
147 | return 0; | |
148 | } | |
149 | #endif |